The present invention relates to covering a rigid or semi-rigid substrate with a flexible covering material. The invention is especially adapted for upholstery applications where a rigid or semi-rigid substrate is covered with at least a layer of flexible upholstery and often a layer of flexible cushion or padding material.
When covering such a substrate, one must not only cover the front and sides of the substrate, but also must wrap the upholstery around to the back side of the substrate. Typically, the marginal edge of the covering material is secured to the back surface of the substrate.
It is common to perform this covering operation by placing the fabric and any cushioning material over a mold cavity, push the substrate down onto the upholstery and cushion and then push the composite into the mold cavity. Fingers or clamps then slide over the upwardly projecting marginal edge of the upholstery and push it down onto the back side of the substrate. Glue is often applied to the back side of the substrate so that when the upholstery is pushed down over it, it is adhered to it.
U.S. Pat. No. 3,438,108 to Nash and U.S. Pat. No. 2,705,522 to Kamborian are exemplary of such prior art upholstering methods and apparatus. U.S. Pat. No. 1,370,690 to Jacobs is similar.
U.S. Pat. No. 3,325,329 to Bolesky discloses an alternative upholstery wrapping approach involving a flexible diaphragm and vacuum forming. The upholstery and cushioning are placed over the substrate, located within a cavity. A flexible diaphragm is then placed over the opening of the cavity and the cavity is evacuated. The flexible diaphragm is drawn down against the strategically located vacuum ports in such a way as to force the margin of the upholstery around to the back side of the rigid or semi-rigid substrate being covered.
The use of sliding clamps or fingers as is typical in such upholstery wrapping operations is complicated and leads to maintenance and wear problems due to the numerous moving parts. The vacuum forming technique of Bolesky is not known to have achieved any substantial commercial success.